AI capital expenditure forecast to exceed the cost of building railways in both the U.S. and the U.K. — with the internet added on top

A new forecast from a leading accounting firm suggests that capital expenditure on artificial intelligence is set to outstrip the combined cost of building the railway networks and the internet in both the United States and the United Kingdom. The firm notes that the AI buildout is not simply a larger version of past infrastructure waves. Its defining feature is the concentration and trajectory of spending: investment is scaling up far faster, compressing what took decades into a few years.

This distinction matters for financial markets. Railways and the internet eventually generated broad economic returns, but their early phases were marked by overinvestment, boom-and-bust cycles, and periods of low returns on capital. The AI investment wave raises similar questions, but with a much faster pace of capital deployment. Investors are likely to focus on whether companies' cash flows can support this level of expenditure, and how quickly AI services will translate into productivity gains or revenue growth. Watching the progression of capital spending relative to actual AI adoption will be key to assessing the durability of this cycle.